The present invention relates generally to food processing and, more particularly, to prolonging the shelf life of meats and vegetables through a process that includes vacuum steam heating and cooling followed by inert atmosphere packaging.
Food processing transforms perishable vegetable and meat products into stable forms that can be stored and shipped to markets without loss of nutritive value or palatability. By using processed foods, consumers gain access to a more diversified diet throughout the year and avoid significant preparation times associated with cleaning, trimming, and cooking fresh foods. While processed foods, particularly canned and frozen foods, can be stored without spoiling for much longer periods than fresh foods, they often exhibit less satisfactory flavor, texture, color, and nutritional value. Canned and frozen food manufacturing practices may compromise these and other organoleptic attributes.
There is growing demand in the retail sector for extended shelf life foods that are convenient to prepare but that maintain the favorable qualities of fresh vegetable and animal meat products. Consumers prefer the favorable sensory characteristics of taste, texture, and color associated with fresh foods, but want the ease of using foods with reduced preparation times. Extended shelf life foods must conform to sterilization regulations as directed by food safety laws, meet manufacturing requirements including extended shelf life and low production cost, and satisfy consumer quality and convenience expectations. However, food processing techniques based on distinct heating, cooling, and packaging operations exhibit mixed success in achieving these objectives. Processes that rely on hot water to blanch or heat vegetable or animal meat products may reduce microorganisms and inhibit certain enzymes associated with food spoilage, but they frequently significantly diminish favorable food qualities such as flavor, texture, color, and nutritional value. Blanching or related hot water treatments additionally may lead to formation of large quantities of wastewater. The use of large quantities of water may require additional production steps and contribute to increased production costs. Processes that rely on water baths or sprays to cool the heat treated vegetable or animal meat products also may lead to formation of large quantities of wastewater and they create added risk of re-exposing partially processed foods to contaminants.
There remains a need for a cost effective food processing method that produces vegetables and animal meats that are safe to consume, possess favorable organoleptic qualities, and have extended shelf lives.
The present invention is directed to processing techniques for preserving and packaging foods with an extended shelf life that helps overcome the shortcomings of conventional processes. The invention includes four basic innovationsxe2x80x94(1) performing the steam cooking and subsequent cooling steps in the same vessel, (2) evacuating the vessel before steam is introduced for cooking, (3) introducing steam into the vessel while the vessel is still under vacuum, and (4) vacuum cooling the cooked food.
Accordingly, in one embodiment of the invention, the process includes the steps of placing a food product in a vessel, cooking the food product in the vessel with steam and then cooling the cooked food product in the same vessel without exposing the food product to cooling water or other potential sources of external contamination.
In a second embodiment, the process includes the steps of placing the food product in the vessel, removing substantially all of the air from the vessel, cooking the food product, and then cooling the cooked food product.
In a third embodiment of the invention, the process includes the steps of placing the food product in the vessel, creating a vacuum in the vessel, introducing steam into the vessel while the vessel is still under vacuum, cooking the food product and then cooling the food product.
In a fourth embodiment, the process includes the steps of placing the food product in the vessel, cooking the food product, and then cooling the cooked food product by vaporizing residual moisture left in the vessel after cooking, including any moisture on or in the food product.
The cooked and cooled food products will typically be unloaded from the vessel to a clean room where they are packaged in sealed containers to prevent microbial recontamination. The processing techniques of the present invention give rise to vegetable or animal meat products with extended shelf lives of up to 45 days if shipped and stored in an environment cooled to 33xc2x0 F.-34xc2x0 F. These processes employ vacuum steaming and cooling techniques that are new and more desirable treatment steps than those processes disclosed in the prior art because they maintain high levels of food sterilization and extended shelf life without significantly impairing food sensory qualities that are favored by consumers. In addition, by using a vessel for both the heating and cooling steps, the processes of the present invention reduce the number of processing steps and minimize the need to change production lines or equipment, lowering production costs for manufacturers and minimizing the risk of exposing partially processed foods to contaminants.
The invention, as summarized above and defined in the claims at the end of this Specification, may be better understood with reference to the drawings and the following detailed description of the preferred embodiment and appended claims.